Method of manufacturing a display device

ABSTRACT

An object of the invention is to improve patterning accuracy while maintaining low cost, high throughput and a high degree of freedom of an optical material in a matrix type display device and a manufacturing method thereof. In order to achieve the object, surface features, including structural surface features, a desired distribution of water repellency, liquid repellency, hydrophilicity and lyophilicity, or a desired potential distribution are formed by utilizing first bus lines in a passive matrix type display device or utilizing scanning lines, signal lines, common feeder lines, pixel electrodes, an interlayer insulation film, or a light shielding layer in an active matrix type display device. A liquid optical material is selectively coated at predetermined positions by utilizing the surface features.

This is a Division of Application No. 09/077,029 filed May 18, 1998,which in turn is a National Stage Application of InternationalApplication No. PCT/JP97/03297 filed Sep. 18, 1997, which claimspriority to Japanese Patent Application No. 8-248087, filed in theJapanese Patent Office on Sep. 19, 1996. The disclosures of the priorapplications are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a matrix type display device and amanufacturing method thereof, and particularly to a matrix type displaydevice having a structure in which an optical material such as afluorescent material (luminescent material), a light modulation materialor the like is selectively arranged at predetermined positions on adisplay substrate, the optical material being liquid at least duringcoating, and a manufacturing method thereof wherein the optical materialcan accurately be arranged at the predetermined positions.

2. Description of Related Art

Matrix type display devices such as an LCD (Liquid Crystal Display), anEL (Electroluminescence) display device, and the like are frequentlyused as various display devices that are light weight, thin, and havehigh image quality and high definition. A matrix type display devicecomprises matrix-formed bus lines, an optical material (luminescentmaterial or light modulation material), and if required, othercomponents.

In a monochromatic matrix type display device, wiring and electrodesmust be arranged in a matrix on the display substrate, but the opticalmaterial can be uniformly coated over the entire surface of the displaysubstrate.

In contrast, for example, when a so-called matrix type color displaydevice is realized by using an EL display device of the type that emitslight by itself, it is necessary to arrange three pixel electrodescorresponding to the primary colors RGB of light for each pixel, andcoat the optical material corresponding to any one of the primary colorsRGB for each pixel electrode. Namely, the optical material must beselectively arranged at the predetermined positions.

SUMMARY OF THE INVENTION

There is thus demand for developing a method of patterning the opticalmaterial. Suitable examples of effective patterning methods includeetching and coating.

The etching process is carried out as follows.

First, a layer of an optical material is formed over the entire surfaceof the display substrate. Then a resist layer is formed on the opticalmaterial layer, exposed to light through a mask and then patterned. Thenthe optical material layer is patterned by etching in correspondencewith the resist pattern.

However, in this case, a large number of steps are required, and each ofthe materials and apparatus used is expensive, thereby increasing thecost. Also a large number of steps are required, and each of the stepsis complicated, thereby deteriorating throughput. Further, dependingupon chemical properties, some optical materials have low resistance toresist and an etchant, and thus these steps are impossible.

On the other hand, the coating process is carried out as follows.

First, an optical material is dissolved in a solvent to form a solution,and the thus-formed solution of the optical material is selectivelycoated at the predetermined positions on the display substrate by an inkjet method or the like. Then, if required, the optical material issolidified by heating, irradiation of light, or the like. In this case,a small number of steps are required, and each of the materials andapparatus used is inexpensive, thereby decreasing the cost. Also, asmall number of steps are required, and each of the steps is simple,thereby improving throughput. Further, these steps are possibleregardless of the chemical properties of the optical material used aslong as a solution of the optical material can be formed.

The coating patterning method is thought to be easily carried out.However, as a result of experiment, the inventors found that in coatingthe optical material by the ink jet method, the optical material must bediluted at least several tens of times with a solvent, and thus thesolution obtained has high fluidity, thereby causing difficulties inholding the solution at the coating positions until it is completelysolidified after coating.

In other words, patterning precision deteriorates due to the fluidity ofthe solution of the optical material. For example, the optical materialcoated in a pixel flows to the adjacent pixels to deteriorate theoptical properties of the pixels. Also variations occur in the coatingareas in the respective pixels, thereby causing variations in thecoating thickness and thus the optical properties of the opticalmaterial.

Although this problem significantly occurs with an optical material forEL display devices or the like, which is liquid during coating and thensolidified, the problem also occurs in cases in which a liquid crystalthat is liquid both during and after coating is selectively coated onthe display substrate.

The present invention has been achieved in consideration of the unsolvedproblem of the prior art, and an object of the invention is to provide amatrix type display device in which a liquid optical material cansecurely be arranged at predetermined positions while maintainingcharacteristics such as low cost, high throughput, a high degree offreedom of the optical material, etc., and a manufacturing methodthereof.

One aspect of the invention relates to a matrix type display devicehaving a structure in which an optical Material is selectively arrangedat predetermined positions on a display substrate, the optical materialbeing liquid at least during coating-at the predetermined positions,wherein a surface feature is formed at each of the predeterminedpositions for selectively coating the optical material.

As used herein, surface feature refers to any one of a structuralsurface feature on a substrate, such as a bump, cavity or otherstructural feature, or other physical features, such as water repellencyhydrophilicity, liquid repellency, lyophilicity or electriccharge/potential distribution.

One aspect of the invention thus permits selective arrangement of theoptical material at the predetermined positions using the surfacefeature even if the optical material is liquid during coating. Namely,the matrix type display device is a high-quality matrix type displaydevice comprising the optical material accurately arranged-at thepredetermined positions.

One aspect of the invention relates to a method of manufacturing amatrix type display device having a structure in which an opticalmaterial is selectively arranged at predetermined positions on a displaysubstrate, the optical material being liquid at least during coating atthe predetermined positions, the method comprising the steps of forminga surface feature at each of the predetermined positions and coating theliquid optical material at-the predetermined positions using the surfacefeatures.

One aspect of invention comprises forming the surface features beforecoating the liquid optical material, and is thus capable of preventingthe liquid optical material coated at the predetermined positions fromspreading to the peripheries thereof. As a result, it is possible toimprove the pattering precision while maintaining characteristics suchas low cost, high throughput, the high degree of freedom of the opticalmaterial, etc.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a structural surface feature, i.e.,difference in height, is formed in a concave shape in which each of thepredetermined positions is lower than the periphery thereof so that theliquid optical material is coated at the predetermined positions withthe surface of the display substrate coated with the liquid opticalmaterial turned upward.

In this aspect of the invention, the surface of the display substratewhich is coated with the optical material is turned upward to turn theconcave portions formed by the difference in height upward. When theliquid optical material is coated on the insides of the concaveportions, the optical material stays in the concave portions due togravity, and the coated liquid optical material can stay in the concaveportions due to gravity, surface tension and the like as long as theamount of the optical material coated is not too large. Therefore, inthis state, the optical material can be solidified by, for example,drying to perform patterning with high precision and with no problem.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the difference in height has a convexshape in which each of the predetermined positions is higher than theperiphery thereof so that the liquid optical material is coated at thepredetermined positions with the surface of the display substrate thatis coated with the optical material turned downward.

In this aspect of the invention, when the surface of the displaysubstrate coated with the optical material is turned downward, theconvex portions formed by the difference in height are also turneddownward. In coating the liquid optical material on the convex portions,the optical material concentrates on the convex portions due to surfacetension, and the coated liquid optical material can stay on the convexportions due to surface tension as long as the amount of the opticalmaterial coated is not too large. Therefore, in this state, the opticalmaterial can be solidified by, for example, drying to perform patterningwith high precision and with no problem.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a plurality offirst bus lines on the display substrate; coating the liquid opticalmaterial; forming surface features at each of the predeterminedpositions on the display substrate for coating the liquid opticalmaterial; coating the liquid optical material at the predeterminedpositions and forming a plurality of second bus lines crossing the firstbus lines to cover the optical material.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a plurality offirst bus lines on the display substrate; forming surface features ateach of the predetermined positions on the display substrate for coatingthe liquid optical material; coating the liquid optical material at thepredetermined positions forming a plurality of second bus lines on apeeling substrate through a peeling layer; and transferring thestructure peeled off from the peeling layer on the peeling substrateonto the display substrate coated with the optical material so that thefirst bus lines cross the second bus lines.

In a method of manufacturing a so-called passive matrix type displaydevice, this aspect of the invention comprises no step of forming alayer for the second bus lines on the upper surface of the opticalmaterial disposed, and then etching the layer, thereby decreasing damageto the base material such as the optical material or the like in thesubsequent step.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming, on the displaysubstrate, wiring including a plurality of scanning lines and signallines, a pixel electrode corresponding to each of the predeterminedpositions, and switching elements for controlling the states of thepixel electrodes in accordance with the state of the wiring; formingsurface features at each of the predetermined positions on the displaysubstrate for coating the liquid optical material; and coating theliquid optical material at the predetermined positions.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming surface featuresat each of the-predetermined positions on the display substrate forcoating the liquid optical material; coating the liquid optical materialat the predetermined positions; forming wiring including a plurality ofscanning lines and signal lines, a pixel electrode corresponding to eachof the predetermined positions, and switching elements for controllingthe states of the pixel electrodes in accordance with the state of thewiring on a peeling substrate through a peeling layer; and transferringthe structure peeled off from the peeling layer on the peeling substrateonto, the display substrate coated with the optical material.

In a method of manufacturing a so-called active-matrix type displaydevice, this aspect of the invention comprises no step of forming alayer for the wiring and a layer for the pixel electrodes on the uppersurface of the optical material disposed, and then etching the layers,thereby decreasing damage to the base material such as the opticalmaterial or the like in-the subsequent step, and damage to the scanninglines, the signal lines, the pixel electrodes or the switching elementsdue to coating of the optical material.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a difference in height is formed byusing the first bus lines and has a concave shape in which each of thepredetermined positions is lower than the periphery thereof so that inthe step of coating the liquid optical material, the liquid opticalmaterial is coated at the predetermined positions with the surface ofthe display substrate coated with the liquid crystal material turnedupward.

In a method of manufacturing a so-called passive matrix type displaydevice, this aspect of the invention comprises the step of forming adifference in height by using the first bus lines. As a result, the stepof forming the first bus lines, in whole or in part, can also be usedas-the step of forming the surface features, thereby suppressing anincrease in the number of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a difference in height is formed byusing the wiring and has a concave shape in which each of thepredetermined positions is lower than the periphery thereof so that inthe step of coating the liquid optical material, the liquid opticalmaterial is coated at the predetermined positions with the surface ofthe display substrate coated with the liquid crystal material turnedupward.

In a method of manufacturing a so-called active matrix type displaydevice, this aspect of the invention comprises the step of forming adifference in height by using the wiring. As a result, part of the wholeof the step of forming the wiring can also be used as the step offorming the surface features, thereby suppressing an increase in thenumber of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a difference in height is formed byusing the pixel electrodes, and has a convex shape in which each of thepredetermined positions is higher than the periphery thereof so that inthe step of coating the liquid optical material, the liquid opticalmaterial is coated at the predetermined positions with the surface ofthe display substrate coated with the liquid crystal material turneddownward.

In a method of manufacturing a so-called active matrix type displaydevice, this aspect of the invention comprises the step of forming adifference in height by using the pixel electrodes. As a result, thestep of forming the wiring, in whole or in part, can also be used as thestep of forming the surface features, thereby suppressing an increase inthe number of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of forming an interlevelinsulation film, wherein a difference in height is formed by using theinterlevel insulation film, and has a concave shape in which each of thepredetermined positions is lower than the periphery thereof so that inthe step of coating the liquid optical material, the liquid opticalmaterial is coated at the predetermined positions with the surface ofthe display substrate coated with the liquid crystal material turnedupward.

In a method of manufacturing a so-called passive matrix type displaydevice and a method of manufacturing a so-called active matrix typedisplay device, this aspect of the invention comprises the step offorming a difference in height by using the interlevel insulation film.As a result, the step of forming the interlevel insulation film, inwhole or in part, can also be used as the step of forming the surfacefeatures, thereby suppressing an increase in the number of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of forming a lightshielding layer, wherein a difference in height is formed by using thelight shielding layer, and has a concave shape in which each of thepredetermined positions is lower than the periphery thereof so that inthe step of coating the liquid optical material, the liquid opticalmaterial is coated at the predetermined positions with the surface ofthe display substrate coated with the liquid crystal material turnedupward.

In a method of manufacturing a so-called passive matrix type displaydevice and a method of manufacturing a so-called active matrix typedisplay device, this aspect of the invention comprises the step offorming a difference in height by using a light shielding layer. As aresult, the step of forming the light shielding layer, in whole or inpart, can also be used as the step of forming the surface features,thereby suppressing an increase in the number of f the steps. One aspectof the invention relates to the method of manufacturing a matrix typedisplay device wherein in the step of forming the difference in height,the difference in height is formed by selectively removing-the coatedliquid material. Resist or the like can be used as the liquid material.In the us-e of resist, the resist is coated over the entire surface ofthe display device by spin coating to form a resist film having anappropriate thickness, followed by exposure and etching of the resistfilm to form a convex portion corresponding to each of the predeterminedpositions, whereby the difference in height can be formed.

This aspect of the invention can simplify the step of forming thedifference in height and can easily form a large difference in heightwhile decreasing damage to the base material.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a difference in height is formed onthe peeling substrate through the peeling layer, and the structurepeeled off from the peeling layer on the peeling substrate istransferred onto the display substrate.

This aspect of the invention comprises the step of transferring thedifference in height separately formed on the peeling substrate.Therefore, the invention can simplify the step of forming the surfacefeatures and can easily form a large difference in height whiledecreasing damage to the base material.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the height dr of the difference inheight satisfies the following equation (1):d_(a)<d_(r)  (1)

wherein d_(a) is the thickness of a single coat of the liquid opticalmaterial.

This aspect of the invention is capable of preventing the opticalmaterial from flowing out to the peripheries of the predeterminedpositions beyond the concave difference in height without contributionof surface tension of the liquid optical material.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the following equation (2) issatisfied:V _(d)/(d _(b) ·r)>E _(t)  (2)

wherein V_(d) is the driving voltage applied to the optical material, dbis the total thickness of the respective coatings of the liquid opticalmaterial, r is the concentration of the liquid optical material, and Etis the minimum electric field strength (threshold electric fieldstrength) at which a change in optical properties of the opticalmaterial occurs.

This aspect of the invention defines the relation between the coatingthickness and the driving voltage, thereby ensuring that the opticalmaterial exhibits an electro-optical effect.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the height dr of the difference inheight satisfies the following equation (3):d_(f)=d_(r)  (3)

wherein df is the thickness of the optical material at the time ofcompletion.

This aspect of the invention ensures flatness of the difference inheight and the optical material at the time of completion, anduniformity in the optical properties of the optical material, and canprevent a short circuit.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the thickness at the time ofcompletion satisfies the following equation (4)V _(d) /d _(f) >E _(t)  (4)

wherein V_(d) is the driving voltage applied to the optical material,and E_(t) is the minimum electric field strength (threshold electricfield strength) at which a change in optical properties of the opticalmaterial occurs.

This aspect of the invention defines the relation between the coatingthickness and the driving voltage, thereby ensuring that the opticalmaterial exhibits an electro-optical effect.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of enhancing the lyophilicityat the predetermined positions on the display device relative to thelyophilicity of the peripheries thereof, and coating the liquid opticalmaterial at the predetermined positions.

In this aspect of the invention since the lyophilicity at thepredetermined positions is enhanced before the liquid optical materialis coated, the liquid optical material coated at the predeterminedpositions more easily stays at the predetermined positions than theperipheries thereof, and the difference in lyophilicity between each ofthe predetermined positions and the periphery thereof is sufficientlyincreased to prevent the liquid optical material coated at thepredetermined positions from spreading to the peripheries thereof. As aresult, it is possible to improve the precision of patterning whilemaintaining the properties such as low cost, high throughput and thehigh degree of freedom of the optical material.

The step of enhancing the lyophilicity at the predetermined positions onthe display substrate relative to the lyophilicity of the peripheriesthereof possibly comprises enhancing the lyophilicity at thepredetermined positions, enhancing the liquid repellency of theperipheries of the predetermined positions, or performing both methods.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a plurality offirst bus lines on the display device, enhancing the lyophilicity at thepredetermined positions on the display device relative to thelyophilicity of the peripheries thereof, coating the liquid opticalmaterial at the predetermined positions, and forming a plurality ofsecond bus lines crossing the first bus lines to cover the opticalmaterial.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a plurality offirst bus lines on the display device, enhancing the lyophilicity at thepredetermined positions on the display device relative to thelyophilicity of the peripheries thereof, coating the liquid opticalmaterial at the predetermined positions, forming a plurality of secondbus lines on a peeling substrate through a peeling layer, andtransferring the structure peeled off from the peeling layer on thepeeling substrate onto the display substrate coated with the opticalmaterial so that the first bus lines cross the second bus lines.

In a method of manufacturing a so-called passive matrix type displaydevice, this aspect of the invention comprises no step of forming alayer for the second bus lines on the disposed optical material andetching the layer. It is thus possible to decrease damage to the basematerial such as the optical material or the like in the subsequentstep.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming, on the displaydevice, wiring including a plurality of scanning lines and signal lines,a pixel electrode corresponding to each of the predetermined positions,and switching elements for controlling the states of the pixelelectrodes in accordance with the state of the wiring; enhancing thelyophilicity at the predetermined positions on the display devicerelative to the lyophilicity of the peripheries thereof, and coating theliquid optical material at the predetermined positions.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of enhancing the lyophilicityat the predetermined positions on the display device relative to thelyophilicity of the peripheries thereof: coating the liquid opticalmaterial at the predetermined positions: forming wiring including aplurality of scanning lines and signal lines, a pixel electrodecorresponding to the each of the predetermined positions, and switchingelements for controlling the states of the pixel electrodes inaccordance with the state of the wiring on a peeling substrate through apeeling layer; and transferring the structure peeled off from thepeeling layer on the peeling substrate onto the display substrate coatedwith the optical material.

In a method of manufacturing a so-called active matrix type displaydevice, this aspect of the invention comprises no step of forming alayer for wiring and a layer for the pixel electrodes on the opticalmaterial disposed and etching these layers. It is thus possible todecrease damage to the base material such as the optical material or thelike in the subsequent step, and damage to the scanning lines, thesignal lines, the pixel electrodes or the switching elements due tocoating of the optical material.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a distribution of high liquidrepellency is formed along the first bus lines on the display substrateto enhance the lyophilicity at the predetermined positions on thedisplay substrate relative to the lyophilicity of the peripheriesthereof.

In a method of manufacturing a so-called passive matrix type displaydevice, this aspect of the invention comprises forming a distribution ofhigh liquid repellency along the first bus lines. As a result, the stepof forming the first bus lines, in whole or in part, can also be used asthe step of enhancing the lyophilicity at the predetermined positionsrelative to the lyophilicity of the peripheries thereof, therebysuppressing an increase in the number of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a distribution of high liquidrepellency is formed along the wiring on the display substrate toenhance the lyophilicity at the predetermined positions on the displaysubstrate relative to the lyophilicity of the peripheries thereof.

In a method of manufacturing a so-called active matrix type displaydevice, this aspect of the invention comprises forming a distribution ofhigh liquid repellency along the wiring. As a result, the step offorming the first bus lines, in whole or in part, can also be used asthe step of enhancing the lyophilicity at the predetermined positionsrelative to the lyophilicity of the peripheries thereof, therebysuppressing an increase in the number of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the lyophilicity of the surfaces ofthe pixel electrodes on the display substrate are enhanced to enhancethe lyophilicity at, the predetermined positions on the displaysubstrate relative to the lyophilicity of the peripheries thereof.

In a method of manufacturing a so-called active matrix type displaydevice, this aspect of the invention comprises enhancing thelyophilicity of the surfaces of the pixel electrodes. As a result, thestep of forming the pixel electrodes, in whole or in part, can also beused as the step of enhancing the lyophilicity at the predeterminedpositions relative to the lyophilicity of the peripheries thereof,thereby suppressing an increase in the number of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of forming an interlevelinsulation film, wherein a distribution of high liquid repellency isformed along the interlevel insulation film on the-display substrate toenhance the lyophilicity at the predetermined positions on the displaysubstrate relative to the lyophilicity of the peripheries thereof.

In a method of manufacturing a so-called s passive matrix type displaydevice, this aspect of the invention comprises forming a distribution ofhigh liquid repellency along the interlevel insulation film. As aresult, the step of forming the interlevel insulation film, in whole orimpart, can also be used as the step of enhancing the lyophilicity atthe predetermined positions relative to the lyophilicity of theperipheries thereof, thereby suppressing an increase in the number ofthe steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of forming an interlevelinsulation film so that the surfaces of the pixel electrodes areexposed, wherein in forming the interlevel insulation film, a differencein height for coating the liquid optical material is formed in theboundary between the portion where the surface of each of the pixelelectrodes is exposed and the periphery thereof, and the liquidrepellency of the surface of the interlevel insulation film is enhancedto enhance the lyophilicity at the predetermined positions on thedisplay substrate relative to the lyophilicity of the peripheriesthereof.

In this aspect of the invention the difference in height is formed in aconcave shape by using the interlevel insulation film before the liquidoptical material is coated, and the liquid repellency of the surface ofthe interlevel insulation film is enhanced to enhance the lyophilicityat the predetermined positions relative to the lyophilicity of theperipheries thereof. Therefore, the liquid optical material coated atthe predetermined positions is prevented from spreading to theperipheries thereof. As a result, it is possible to further improve thepatterning precision while maintaining the properties such as low cost,high throughput and the high degree of freedom of the optical material.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of forming a lightshielding layer, wherein a distribution of high liquid repellency isformed along the light shielding layer on the display substrate toenhance the lyophilicity at the predetermined positions on the displaysubstrate relative to the lyophilicity of the peripheries thereof.

In a method of manufacturing a so-called passive matrix type displaydevice and a method of manufacturing a so-called active matrix type Odisplay device, this aspect of the invention comprises forming adistribution of high liquid repellency along the light shielding layer.As a result, the step of forming the light shielding layer, in whole orin part, can also be used as the step of enhancing the lyophilicity atthe predetermined positions relative to the lyophilicity of theperipheries thereof, thereby suppressing an increase in the number ofthe steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein a difference in lyophilicity betweeneach of the predetermined positions and the periphery thereof isincreased by irradiating ultraviolet rays or plasma of O₂, CF₃, Ar orthe like.

Thus, this aspect of the invention is capable of easily enhancing theliquid repellency of the surface of the interlevel insulation film, forexample.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of enhancing thelyophilicity at the predetermined positions on the display substraterelative to the lyophilicity of the peripheries thereof.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of forming a differencein height in the boundary between each of the predetermined positions onthe display substrate and the periphery thereof, for coating the liquidoptical material.

One aspect of the invention comprises forming a predetermined differencein height and enhancing the lyophilicity at the predetermined positionsrelative to the lyophilicity of the peripheries thereof before theliquid optical material is coated. Therefore, this aspect of theinvention securely prevents the liquid optical material coated at thepredetermined positions from spreading to the peripheries thereof. As aresult, it is possible to further improve the patterning precision whilemaintaining the properties such as low cost, high throughput and thehigh degree of freedom of the optical material.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a potentialdistribution on the display substrate so that the potential at each ofthe predetermined positions is different from that of the peripherythereof, and selectively coating the liquid optical material at thepredetermined positions by using the potential distribution.

This aspect of the invention comprises forming a potential distributionbefore the liquid optical material is coated so that the liquid opticalmaterial coated at the predetermined positions can be prevented fromspreading to the peripheries thereof by the potential distribution. As aresult, it is possible to improve the patterning precision whilemaintaining the properties such as low cost, high throughput and thehigh degree of freedom of the optical material.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a potentialdistribution on the display substrate so that the potential at each ofthe predetermined positions is different from that of the peripherythereof, and coating the liquid optical material at the predeterminedpositions after charging the optical material to a potential where arepulsive force is generated between each of the predetermined positionsand the periphery thereof.

This aspect of the invention comprises generating a repulsive forcebetween the liquid optical material that is coated at the predeterminedpositions and the peripheries thereof so as to prevent the liquidoptical material coated at the predetermined positions from spreading tothe peripheries thereof. As a result, it is possible to improve thepatterning precision while maintaining the properties such as low cost,high throughput and the high degree of freedom of the optical material.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a plurality offirst bus lines on the display substrate, forming a potentialdistribution on the display substrate so that the potential at each ofthe predetermined positions is different from that of the peripherythereof, coating the liquid optical material at the predeterminedpositions after charging the optical material to a potential where arepulsive force is generated between each of the predetermined positionsand the periphery thereof, and forming a plurality of second bus linescrossing the first bus lines to cover the optical material.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming a plurality offirst bus lines on the display substrate, forming a potentialdistribution on the display substrate so that the potential at each ofthe predetermined positions is different from that of the peripherythereof, coating the liquid optical material at the predeterminedpositions after charging the optical material to a potential at which arepulsive force is generated between each of the predetermined positionsand the periphery thereof, forming a plurality of second bus lines on apeeling substrate through a peeling layer, and transferring thestructure peeled off from the peeling layer on the peeling substrateonto the display substrate coated with the optical material so that thefirst bus lines cross the second bus lines.

In a method of manufacturing a so-called passive matrix type displaydevice, this aspect of the invention comprises no step of forming alayer for the second bus lines on the upper surface of the disposedoptical material and etching the layer, thereby decreasing damage to thebase material such as the optical material or the- like in thesubsequent step.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions, the method comprising the steps of forming on the displaysubstrate wiring including a plurality of scanning lines and signallines, a pixel electrode corresponding to each of the predeterminedpositions and switching elements for controlling the states of the pixelelectrodes in accordance with the state of the wiring, forming apotential distribution on the display substrate so that the potential ateach of the predetermined positions is different from that of theperiphery thereof, and coating the liquid optical material at thepredetermined positions after charging the optical material to apotential at which a repulsive force is generated between each of thepredetermined positions and the periphery thereof.

One aspect of the invention relates to a method of manufacturing amatrix type display device comprising an optical material selectivelydisposed at predetermined positions on a display device, the opticalmaterial being liquid at least during coating at the predeterminedpositions. The method comprises the steps of forming a potentialdistribution on the display substrate so that the potential at each ofthe predetermined positions is different from that of the peripherythereof, coating the liquid optical material at the predeterminedpositions after charging the optical material to a potential at which arepulsive force is generated between each of the predetermined positionsand the periphery thereof, forming wiring including a plurality ofscanning lines and signal lines, a pixel electrode corresponding to eachof the predetermined positions and switching elements for controllingthe states of the pixel electrodes in accordance with the state of thewiring on a peeling substrate through a peeling layer, and transferringthe structure peeled off from the from the peeling layer on the peelingsubstrate onto the display substrate coated with the optical material.

In a method of manufacturing a so-called active matrix type displaydevice, this aspect of the invention comprises no step of forming alayer for the wiring and a layer for the pixel electrodes on the uppersurface of the disposed optical material and etching these layers,thereby decreasing damage to the base material such as the opticalmaterial or the like in the subsequent step, and damage to the scanninglines, the signal lines, the pixel electrodes or the switching elementsdue to coating of the optical material.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the potential distribution is formedso that at least the peripheries of the predetermined positions onthe-display substrate are charged.

Thus, this aspect of the invention is capable of securely generating arepulsive force by charging the liquid optical material.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the potential distribution is formedby applying a voltage to the first bus lines.

One aspect of the invention relates to the method of manufacturing amatrix 10 type display device wherein the potential distribution isformed by applying a voltage to the wiring.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the potential distribution ‘I isformed by applying a voltage to the pixel electrodes. The invention inaccordance with claim 44 relates to the method of manufacturing a matrixtype display device of the invention in accordance with claim 38,wherein the potential distribution—is formed by successively applying avoltage to the scanning lines, and at the same time, applying a voltageto the signal lines, and applying a voltage to the pixel electrodesthrough the switching elements.

One aspect of the invention relates to the method of manufacturing amatrix type display device comprising the step of forming a lightshielding layer so that the potential distribution is formed by applyinga voltage to the light shielding layer.

One aspect of the invention comprises forming the potential distributionby using a component of the matrix type display device, and is thuscapable of preventing an increase in the number of the steps.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the potential distribution is formedso that each of the predetermined positions has a polarity opposite tothat of the periphery thereof.

In this aspect of the invention an attractive force is generated betweenthe liquid optical material and each of the predetermined positions, andrepulsive force is generated between the liquid optical material and theperipheries of the predetermined positions, thereby making the opticalmaterial easy to stay at the predetermined positions, and improving thepatterning precision.

In the method of manufacturing a matrix type display device in oneaspect of the invention, an inorganic or organic fluorescent material(luminescent material) can be used as the optical material. As thefluorescent material (luminescent material), an EL (Electroluminescent)material is suitable. In order to obtain the liquid optical material,the optical material may be dissolved in an appropriate solvent.

In the method of manufacturing a matrix type display device in oneaspect of the invention a liquid crystal can also be used as the opticalmaterial.

One aspect of the invention relates to the method of manufacturing amatrix type display device wherein the switching elements are formed byusing amorphous silicon, polycrystalline silicon formed by a hightemperature process at 600° C. or higher, or polycrystalline siliconformed by a low temperature process at 600° C. or lower.

This aspect of the invention can also improve the precision ofpatterning of the optical material. Particularly, in the use ofpolycrystalline silicon formed by a low temperature process, it ispossible to decrease the cost by using a glass substrate, and improveperformance due to high mobility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a circuit showing a portion. of a display devicein accordance with a first embodiment of the present invention.

FIG. 2 is an enlarged plan view showing the plane structure of a pixelregion.

FIGS. 3(a) to 5(d) are drawings showing the flow of a manufacturingprocess in accordance with the first embodiment.

FIG. 6 is a sectional view showing a modified embodiment of the firstembodiment.

FIGS. 7(a) and 7(b) are a plan view and sectional view showing a secondembodiment.

FIG. 8 is a sectional view showing a portion of a manufacturing processin accordance with a third embodiment.

FIG. 9 is a sectional view showing a portion of a manufacturing processin accordance with a fourth embodiment.

FIG. 10 is a sectional view showing a portion of a manufacturing processin accordance with a fifth embodiment.

FIG. 11 is a sectional view showing a portion of a manufacturing processin accordance with a sixth embodiment.

FIG. 12 is a sectional view showing a portion of a manufacturing processin accordance with an eighth embodiment.

FIG. 13 is a sectional view showing a modified embodiment of the eighthembodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowon the basis of the drawings.

(1) First Embodiment

FIGS. 1 to 5(d) are drawings illustrating a first embodiment of thepresent invention. In this embodiment, a matrix type display device anda manufacturing method thereof of the present invention are applied toan active matrix type EL display device. Specifically, these drawingsshow an embodiment in which a luminescent material as an opticalmaterial is coated, and scanning lines, signal lines and common currentsupply lines serve as wiring.

FIG. 1 is a drawing of a circuit showing a portion of a display device 1in this embodiment. The display device 1 comprises wiring including aplurality of scanning lines 131, a plurality of signal lines 132extending in the direction crossing the scanning lines 131, and aplurality of common current supply lines 133 extending parallel to thesignal lines 132; and a pixel region 1A provided for each of theintersections of the scanning lines 131 and the signal lines 132.

For the signal lines 132, a data side driving circuit 3 comprising ashift register, a level shifter, a video line, and an analog switch isprovided. For the scanning lines 131, a scanning side driving circuit 4comprising a shift register and a level shifter is provided. Provided ineach pixel region 1A are: a switching thin film transistor 142 in whicha scanning signal is supplied to a gate electrode through a scanningline 131, a storage capacitor cap for holding an image signal suppliedfrom a signal line 132 through the switching thin film transistor 142, acurrent thin film transistor 143 in which the image signal held by thestorage capacitor cap is supplied to a gate electrode, a pixel electrode141 to which a driving current flows from a common current supply line133 at the time of electrical connection to the common current supplyline 133 through the current thin film transistor 143, and a lightemitting element 140 held between the pixel electrode 141 and areflection electrode 154.

In this configuration, when the switching thin film transistor 142 isturned on by driving the scanning lines 131, the potential of the signallines 132 is held by the storage capacitor cap, and the on-off state ofthe current thin film transistor 143 is determined in accordance withthe state of the storage capacitor cap. Then a current flows to thepixel electrode 141 from the common current supply lines 133 through thechannel of the current thin film transistor 143, and a current flows tothe reflection electrode 154 through the light emitting element 140,whereby the light emitting element 140 emits light in accordance withthe amount of the current flowing therethrough.

Each of the pixel regions 1A has a planar structure in which the pixelelectrode 141 having a rectangular planar shape is arranged so that thefour sides thereof are surrounded by a signal line 132, a common currentsupply line 133, a scanning line 131 and a scanning line for anotherpixel electrode, as shown in FIG. 2 which is an enlarged plan view-withthe reflection electrode and the light emitting element removed.

FIGS. 3(a) to 5(d) are sectional views successively showing the stepsfor manufacturing the pixel region 1A, and correspond to a section takenalong line-A-A in FIG. 2. The process for manufacturing the pixel region1A is described with reference to FIGS. 3(a) to 5(d).

First, as shown in FIG. 3(a), on a transparent display substrate 121 isformed a base protective film (not shown) comprising a silicon oxidefilm having a thickness of about 2000 to 5000 angstroms by a plasma CVDmethod using TEOS (tetraethoxysilane) and oxygen gas as raw materialgases according to demand. Next, the temperature of the displaysubstrate 121 is set to about 350° C., and on the surface of the baseprotective film is formed a semiconductor film 200 comprising anamorphous silicon film having a thickness of about 300 to 700 angstromsby the plasma CVD method. The semiconductor film 200 comprising anamorphous silicon film is then subjected to the crystallization step bylaser annealing or solid phase growth to crystallize the semiconductorfilm 200 to a polysilicon film. In laser annealing, for example, anexcimer laser line beam having a long dimension of 400 mm and an outputstrength of, for example, 200 mJ/cm2 is used. The line beam is scannedso that a portion thereof corresponding to 90% of the laser strengthpeak in the direction of the short dimension is applied to each of theregions.

Next, as shown in FIG. 3(b), the semiconductor film 200 is patterned toform an island-like semiconductor film 210, and on the surface of thesemiconductor film 210 is formed a gate insulating film 220, comprisinga silicon oxide film or nitride film having a thickness of about 600 to1500 angstroms, by the plasma CVD method using TEOS (tetraethoxysilane)and oxygen gas as raw material gases. Although the semiconductor film210 is used for the channel region and source/drain regions of thecurrent thin film transistor 143, another semiconductor film is alsoformed for forming the channel region and source/drain regions of theswitching thin film transistor 142 in another sectional view. Namely, inthe manufacturing process shown in FIGS. 3(a) to 5(d), two types oftransistors 142 and 143 are simultaneously formed, but both transistorsare formed according to the same procedure. Therefore, with respect tothe transistors, only the current thin film transistor 143 is describedbelow, and description of the switching thin film transistor 142 isomitted.

Next, as shown in FIG. 3(c), a conductive film comprising a metallicfilm of aluminum, tantalum, molybdenum, titanium, tungsten, or the likeis formed by a sputtering method, and then patterned to form a gateelectrode 143A.

In this state, a high concentration of phosphorus ions is implanted toform source and drain regions 143 a and 143 b in the silicon thin film210 in self-alignment to the gate electrode 143. A portion into whichthe impurity is not introduced serves as a channel region 143 c.

Next, as shown in FIG. 3(d), an interlevel insulation film 230 isformed, contact holes 232 and 234 are formed, and then trunk electrodes236 and 238 are buried in the contact holes 232 and 234, respectively.

Next, as shown in FIG. 3(e), on the interlevel insulation film 230 areformed a signal line 132, a common current supply line 133 and ascanning line (not shown in FIG. 3). Each of the signal lines 132, thecommon current supply lines 133 and the scanning lines is formedsufficiently thick regardless of the required thickness as wiring.Specifically, each of the lines is formed to a thickness of about 1 to 2um. The trunk electrode 238 and each of the lines may be formed in thesame step. In this case, the trunk electrode 238 is formed of an ITOfilm which will be described below.

Then an interlevel insulation film 240 is formed to cover the uppersurfaces of the lines, a contact hole 242 is formed at a positioncorresponding to the trunk electrode 236, and an ITO film is formed tofill the contact hole 242 therewith, followed by patterning of the ITOfilm to form a pixel electrode 141 electrically connected to the sourceand drain region 143 a at the predetermined position surrounded by thesignal line 132, the common current supply line 133 and the scanningline.

In FIG. 3(e), the portion between the signal line 132 and the commoncurrent supply line 133 corresponds to the predetermined position wherethe optical material is arranged. A structural surface feature, ordifference in height 111 is formed between the predetermined positionand the periphery thereof by the signal line 132 and the common currentsupply line 133. Specifically, the difference in height 111 is formed ina concave shape in which the predetermined position is lower than theperiphery thereof.

Next, as shown in FIG. 4(a), a liquid (a solution in a solvent) opticalmaterial (precursor) 114A for forming a hole injection layercorresponding to a lower layer of the light emitting element 140 isdischarged by an ink jet head method with the upper side of the displaysubstrate 121 turned upward to selectively coat the optical material onthe region (the predetermined position) surrounded by the difference inheight 111. Since detailed contents of the ink jet method are notincluded in the gist of the present invention, the contents are omitted(For such a method, refer to Japanese Unexamined Patent Publication Nos.56-13184 and 2167751, for example).

Materials for forming the hole injection layer includepolyphenylenevinylene obtained from polytetrahydrothiophenylphenylene asa polymer precursor, 1,1-bis-(4-N,N-ditolylaminophenyl)cyclohexane,tris(8hydroxyquinolynol) aluminum, and the like.

At this time, although the liquid precursor 114A has high fluidity andtends to horizontally spread, the difference in height 111 is formed tosurround the coating position, thereby preventing the liquid precursor114A from spreading to the outside of the predetermined position beyondthe difference in height 111 as long as the amount of the liquidprecursor 114A coated in a single application is not excessivelyincreased.

Next, as shown in FIG. 4(b), the solvent of the liquid precursor 114A isevaporated by heating or light irradiation to form a thin, solid holeinjection layer 140 a on the pixel electrode 141. Depending upon theconcentration of the liquid precursor 114A, only a thin hole injectionlayer 140 a is formed. Therefore, where a thicker hole injection layer140 a is required, the steps shown in FIGS. 4(a) and (b) are repeatedlyexecuted a necessary number of times to form the hole injection layer140A having a sufficient thickness, as shown in FIG. 4(c).

Next, as shown in FIG. 5(a), a liquid (a solution in a solvent) of anoptical material (organic fluorescent material) 114B for forming anorganic semiconductor film corresponding to an upper layer of the lightemitting element 140 is discharged by the ink jet head method with theupper surface of the display substrate 121 turned upward to selectivelycoat the optical material on the region (the predetermined position)surrounded by the difference in height 111.

Organic fluorescent materials include cyanopolyphenylenevinylene,polyphenylenevinylene, polyalkylphenylene,2,3,6,7-tetrahydro-11-oxo1H,5H,11H(1)benzopyrano[6,7,8-ij]-quinolizine-10carboxylic acid,1,1-bis-(4-N,N-ditolylaminophenyl)cyclohexane,2-13′,4′dihydroxyphenyl)-3,5,7-trihydroxy-1-benzopyrylium perchlorate,tris(8-hydroxyquinolynol)aluminum,2,3,6,7-tetrahydro-9-methyl-11-oxo-1H,5H,11H(1)benzopyrano[6,7,8-ij]-quinolizine, aromatic diamine derivatives (TDP),oxydiazole dimers (OXD), oxydiazole derivatives (PBD), distyrylarylenederivatives (DSA), quinolynol metal complexes, beryllium-benzoquinolynolderivatives (Bebq), triphenylamine derivatives (MTDATA), distyrylderivatives, pyrazoline dimers, rubrene, quinacridone, triazolederivatives, polyphenylene, polyalkylfluorene, polyalkylthiophene,azomethine zinc complexes, porphyrin zinc complexes, benzoxazole zinccomplexes, phenanthroineeuropiem complexes, and the like.

At this time, although the liquid organic fluorescent material 114B hashigh fluidity and tends to horizontally spread, the difference in height111 is formed to surround the coating position, thereby preventing theliquid organic fluorescent material 114B from spreading to the outsideof the predetermined position beyond the difference in height 111 aslong as the amount of the liquid organic fluorescent material 114Bcoated in a single application is not excessively increased.

Next, as shown in FIG. 5(b), the solvent of the liquid organicfluorescent material 114B is evaporated by heating or light irradiationto form a solid organic semiconductor thin film 140 b on the holeinjection layer 140A. Depending upon the concentration of the liquidorganic fluorescent material 114B, only a thin organic semiconductorfilm 140 b is formed. Therefore, where a thicker organic semiconductorlayer 140 b is required, the steps shown in FIGS. 5(a) and (b) arerepeatedly executed a necessary number of times to form the organicsemiconductor film 140B having a sufficient thickness, as shown in FIG.5(c).

The hole injection layer 140A and the organic semiconductor film 140Bconstitute the light emitting element 140. Finally, as shown in FIG.5(d), the reflection electrode 154 is formed over the entire surface ofthe display substrate 121 or in stripes.

In this embodiment, lines such as the signal line 132, the commoncurrent supply line 133, and the like are formed to surround theprocessing position where the light emitting element 140 is arranged,and are formed to have a thickness larger than the normal thickness toform the difference in height 111, and the liquid precursor 114A and theliquid organic fluorescent material 114B are selectively coated.Therefore, this embodiment has the advantage that the patterningprecision of the light emitting element 140 is high.

Although the formation of the difference in height 111 causes thereflection electrode 154 to have a surface with relatively largeunevenness, the possibility of producing a trouble such as disconnectionor the like is significantly decreased by increasing the thickness ofthe reflection electrode 154 to some extent.

In addition, since the difference in height 111 is formed by using thelines such as the signal line 132, the common current supply line 133,and the like, a new step is not added, and the manufacturing process isnot significantly complicated.

In order to securely prevent the liquid precursor 114A and the liquidorganic fluorescent material 11 4B from flowing out from the inside ofthe difference in height 111, the following relation is preferablyestablished between the coating thickness da of the liquid precursor114A and the liquid organic fluorescent material 114B and the height drof the difference in height 111.d_(a)<d_(r)  (1)

However, when the liquid organic fluorescent material 114E is coated,the hole injection layer 140 A has already been formed, and thus theheight dr of the difference in height 111 must be considered as a valueobtained by subtracting the thickness of the hole injection layer 140Afrom the initial thickness.

Also, equation (1) is satisfied, and the following relation isestablished between the driving voltage Vd applied to the organicsemiconductor film 140B, the total thickness db of the liquid organicfluorescent material 114B, the concentration r of the liquid organicfluorescent material 114B, and the minimum electric field strength Et(threshold electric field strength) at which a change in opticalproperties of the organic semiconductor film 140B occurs.V _(d)/(d _(b) ·r)>E _(t)  (2)In this case, the relation between the coating thickness and the drivingvoltage is defined, and it is ensured that the organic semiconductorfilm 140E exhibits an electro-optical effect.

On the other hand, in order to ensure the flatness of the difference inheight 111 and the light emitting element 140 and uniformity in changesin the optical properties of the organic semiconductor film 140B, andprevent short circuit, the following relation may be established betweenthe thickness df of the light emitting

element 140 at the time of completion and the height dr of thedifference in height 111:d_(f)=d_(r)  (3)

In addition, if equation (3) is satisfied, and the following equation(4) is satisfied, the relation between the thickness of the lightemitting element 140 at the time of completion and the driving voltageis defined, and it is ensured that the organic fluorescent materialexhibits an electro-optical effect.V _(d) /d _(f) >E _(t)  (4)

However, in this case, the thickness df is the thickness of the organicsemiconductor film 140B at the time of completion, not the thickness ofthe entire light emitting element 140.

The optical material which forms the upper layer of the light emittinglayer 140 is not limited to the organic fluorescent material 114B, andan inorganic fluorescent material may be used.

Each of the transistors 142 and 143 as switching elements is preferablymade of polycrystalline silicon formed by a low temperature process at600° C. or less, thereby achieving low cost by using a glass substrate,and high performance due to high mobility. The switching elements may bemade of amorphous silicon or polycrystalline silicon formed by a hightemperature process at 600° C. or higher.

Besides the switching thin film transistor 142 and the current thin filmtransistor 143, another transistor may be provided, or a system ofdriving by only one transistor may be used.

The difference in height 111 may be formed by using the first bus linesin a passive matrix display device, the scanning lines 131 in an activematrix display device, or the light shielding layer.

In the light emitting element 140, the hole injection layer 140A may beomitted, though the efficiency of light emission (rate of holeinjection) slightly deteriorates. Alternatively, an electron injectionlayer is formed between the organic semiconductor film 140E and thereflection electrode 154 in place of the hole injection layer 140A, orboth the hole injection layer and the electron injection layer may beformed.

Although, in this embodiment, the entire light emitting element 140 isselectively arranged in consideration of color display, for example, ina monochrome display device 1, the organic semiconductor film 140B maybe uniformly formed over the entire surface of the display substrate121, as shown in FIG. 6. However, even in this case, the hole injectionlayer 140A must be selectively arranged at each of the predeterminedpositions in order to prevent crosstalk, and thus it is significantlyeffective to coat the optical material by using the difference in height111.

(2) Second Embodiment

FIG. 7 is a drawing showing a second embodiment of the present inventionin which a matrix type display device and a manufacturing method thereofin accordance with the present invention are applied to a passive matrixtype display device using an EL display device.

FIG. 7(a) is a plan view showing the arrangement of a plurality of firstbus lines 300 and a plurality of second bus lines 310 arrangedperpendicularly to the first bus lines 300, and FIG. 7(b) is a sectionalview taken along line B-B in FIG. 7(a). The same components as the firstembodiment are denoted by the same reference numerals, and descriptionthereof is omitted. Since details of the manufacturing process are alsothe same as the first embodiment, the process is not shown in thedrawings nor described.

Namely, in this embodiment, an insulation film 320 of Si02, for example,is arranged to surround the predetermined position where the lightemitting element 140 is disposed, to form the difference in height 111between the predetermined position and the periphery thereof.

Like the first embodiment, this structure is capable of preventing theliquid precursor 114A and the liquid organic fluorescent material 114Bfrom flowing out to the periphery during selective coating, and has theadvantage of achieving high-precision patterning.

(3) Third Embodiment

FIG. 8 is a drawing showing a third embodiment of the present inventionin which, like in the first embodiment, a matrix type display device anda manufacturing method thereof in accordance with the present inventionare applied to an active matrix type EL display device. Specifically,the difference in height 111 is formed by using the pixel electrode 141,thereby permitting high-precision patterning. The same components as theabove embodiments are denoted by the same reference numerals. FIG. 8 isa sectional view showing an intermediate step of the manufacturingprocess, and the steps before and after this step are not shown nordescribed because they are substantially the same as the firstembodiment.

Namely, in this embodiment, the pixel electrode 141 is formed to have athickness larger than—a normal thickness to form the difference inheight 111 between the pixel electrode 141 and the periphery thereof. Inother words, in this embodiment, the difference in height 111 is formedin a convex shape in which the pixel electrode 141 later coated with theoptical material is higher than the periphery thereof.

Like in the first embodiment, in order to form the hole injection layercorresponding to the lower layer of the light emitting element 140, theliquid (a solution in a solvent) optical material (precursor) 114A isdischarged to coat the optical material on the upper surface of thepixel electrode 141.

However, unlike in the first embodiment, the liquid precursor 114A iscoated on the display substrate while the display substrate is reversed,i.e., in the state where the upper surface of the pixel electrode 141that is coated with the precursor 114A is turned downward.

As a result, the liquid precursor 114A stays on the upper surface of thepixel electrode due to gravity and surface tension, and does not spreadto the periphery thereof. Therefore, the liquid precursor 114A can besolidified by heating or light irradiation to form the same thin holeinjection layer as shown in FIG. 4(b), and this step is repeated to formthe hole injection layer. The organic semiconductor film can also beformed by the same method.

In this way, in this embodiment, the liquid optical material is coatedby using the difference in height 111 formed in a convex shape, therebyimproving patterning precision of the light emitting element.

The amount of the liquid optical material staying on the upper surfaceof the pixel electrode 141 may be adjusted by using inertial force suchas centrifugal force or the like.

(4) Fourth Embodiment

FIG. 9 is a drawing showing a fourth embodiment of the present inventionin which like in the first embodiment, a matrix type display device anda manufacturing method thereof in accordance with the present inventionare applied to an active matrix type EL display device. The samecomponents as the above embodiments are denoted by the same referencenumerals. FIG. 9 is a sectional view showing an intermediate step of themanufacturing process, and the steps before and after this step are notshown nor described because they are substantially the same as the firstembodiment.

Namely, in this embodiment, first the reflection electrode 154 is formedon the display substrate 121, and then the insulation film 320 is formedon the reflection electrode 154 to surround the predetermined positionwhere the light emitting element 140 is arranged later, and to form thedifference in height 111 in a concave shape in which the predeterminedposition is lower than the periphery thereof.

Like in the first embodiment, the liquid optical material is thenselectively coated in the region surrounded by the difference in height111 by the ink jet method to form the light emitting element 140.

On the other hand, scanning lines 131, signal lines 132, pixelelectrodes 141, switching thin film transistors 142, current thin filmtransistors 143 and an insulation film 240 are formed on a peelingsubstrate 122 through a peeling layer 152.

Finally, the structure peeled off from the peeling layer 152 on thepeeling substrate 122 is transferred onto the display substrate 121.

In this embodiment, the liquid optical material is coated by using thedifference in height 111, thereby permitting patterning with highprecision.

Further, in this embodiment, it is possible to decrease damage to thebase material such as the light emitting element 140 in subsequentsteps, or damage to the scanning lines 131, the signal lines 132, thepixel electrodes 141, the switching thin film transistors 142, thecurrent thin film transistors 143 or the insulation film 240, due tocoating of the optical material.

Although, in this embodiment, an active matrix type display device isdescribed, a passive matrix type display device may be used.

(5) Fifth Embodiment

FIG. 10 is a drawing showing a fifth embodiment of the present inventionin which like in the first embodiment, a matrix type display device anda manufacturing method thereof in accordance with the present inventionare applied to an active matrix type EL display device. FIG. 10 is asectional view showing an intermediate step of the manufacturingprocess, and the steps before and after this step are not shown nordescribed because they are substantially the same as the firstembodiment.

Namely, in this embodiment, the difference in height 111 is formed in aconcave shape by using the interlevel insulation film 240 to obtain thesame operation and effect as the first embodiment.

Also, since the difference in height 111 is formed by using theinterlevel insulation film 240, a new step is not added, and thus themanufacturing process is not significantly complicated.

(6) Sixth Embodiment

FIG. 11 is a drawing showing a sixth embodiment of the present inventionin which like in the first embodiment, a matrix type display device anda manufacturing method thereof in accordance with the present inventionare applied to an active matrix type EL display device. The samecomponents as the above embodiments are denoted by the same referencenumerals. FIG. 11 is a sectional view showing an intermediate step ofthe manufacturing process, and the steps before and after this step arenot shown and described because they are substantially the same as thefirst embodiment.

Namely, in this embodiment, the difference in height 111 is not used forimproving pattering precision, but the hydrophilicity of thepredetermined position where the liquid optical material is coated isenhanced relative to the hydrophilicity of the periphery thereof toprevent the coated liquid optical material from spreading to theperiphery.

Specifically, as shown in FIG. 11, the interlevel insulation film 240 isformed, and then an amorphous silicon layer 155 is formed on the uppersurface of the interlevel insulation film 240. Since the amorphoussilicon layer 155 has high water repellency relative to ITO which formsthe pixel electrode 141, a distribution of water repellency andhydrophilicity is formed in which the hydrophilicity of the surface ofthe pixel electrode 141 is high relative to the hydrophilicity of theperiphery thereof.

Like in the first embodiment, the liquid optical material is thenselectively coated on the upper surface of the pixel electrode 141 bythe ink jet method to form the light emitting element 140, and finallythe reflection electrode is formed.

In this way, even in this embodiment, the liquid optical material iscoated after a desired distribution of water repellency andhydrophilicity is formed, and thus the patterning precision can beimproved.

Of course, this embodiment can also be applied to a passive matrix typedisplay device.

Also this embodiment may comprise the step of transferring the structureformed on the peeling substrate through the peeling layer 152 onto thedisplay substrate 121.

Although, in this embodiment, the desired distribution of waterrepellency and hydrophilicity is formed by using the amorphous siliconlayer 155, the distribution of water repellency and hydrophilicity maybe formed by using a metal, an anodic oxide film, an insulation film ofpolyimide, silicon oxide, or the like, or other materials. In a passivematrix display device, the distribution may be formed by using the firstbus lines, and in an active matrix type display device, the distributionmay be formed by using the scanning lines 131, the signal lines 132, thepixel electrodes 141, the insulation film 240 or the light shieldinglayer.

Although, in this embodiment, description is made on the assumption thatthe liquid optical material is an aqueous solution, a solution of anoptical material in another liquid may be used.

In this case, liquid repellency and lyophiiicity to this solution may berequired.

(7) Seventh Embodiment

A seventh embodiment of the present invention has the same sectionalstructure as the fifth embodiment shown in FIG. 10, and is thusdescribed with reference to FIG. 10.

Namely, in this embodiment, the interlevel insulation film 240 is formedby using Si02, and the surface of the interlevel insulation film 240 isirradiated with ultraviolet rays. Then the surface of the pixelelectrode 141 is exposed, and the liquid optical material is selectivelycoated thereon.

In this manufacturing process, not only the difference in height 111 isformed, but also a distribution of high liquid repellency is formedalong the surface of the interlevel insulation film 240, therebyenabling the coated liquid optical material to easily stay at thepredetermined position due to both effects, i.e., the difference inheight 111 and the liquid repellency of the interlevel insulation film240. Namely, since the effects of both the fifth embodiment and thesixth embodiment are exhibited, the patterning precision of the lightemitting element 140 can further be improved.

The time of ultraviolet irradiation may be before or after the surfaceof the pixel electrode 141 is exposed, and may be appropriately selectedin accordance with the material for forming the interlevel insulationfilm 240 and the material for forming the pixel electrode 141. Whereultraviolet irradiation is carried out before the surface of the pixelelectrode 141 is exposed, since the inner wall of the difference inheight 111 has low liquid repellency, the liquid optical materialadvantageously stays in the region surrounded by the difference inheight 111. Conversely, where ultraviolet irradiation is carried outafter the surface of the pixel electrode 141 is exposed, it is necessaryto perform vertical irradiation of ultraviolet rays so as to prevent anincrease in the liquid repellency of the inner wall of the difference inheight 111. However, since ultraviolet irradiation is performed afterthe etching step for exposing the surface of the pixel electrode 141,there is the advantage of eliminating the possibility that the liquidrepellency deteriorates in the etching step.

As the material for forming the interlevel insulation film 240, forexample, photoresist or polyimide may be used. These materials have theadvantage that the film can be formed by spin coating.

For some materials forming the interlevel insulation film 240, liquidrepellency may be enhanced by irradiation of plasma of 02, CF3, Ar orthe like, for example, in place of ultraviolet irradiation.

(8) Eighth Embodiment

FIG. 12 is a drawing showing an eighth embodiment of the presentinvention in which, like in the-first embodiment, a matrix type displaydevice and a manufacturing method thereof in accordance with the presentinvention are applied to an active matrix type EL display device. Thesame components as the above embodiments are denote.d by the samereference numerals. FIG. 12 is a sectional view showing an intermediatestep of the manufacturing process, and the steps before and after thisstep are not shown nor described because they are substantially the sameas the first embodiment.

Namely, in this embodiment, neither the difference in height 111 nor thedistribution of liquid repellency and lyophilicity is used for improvingthe patterning precision, but the patterning precision is improved byusing attraction force and repulsive force due to a potential.

As shown in FIG. 12, the signals lines 132 and the common current supplylines 133 are driven, and the transistors not shown are turned on andoff to form a potential distribution in which the pixel electrode 141has a negative potential, and the interlevel insulation film 240 has apositive potential. Then the positively charged liquid optical material114 is selectively coated at the predetermined position by the ink jetmethod.

In this way, in this embodiment, a desired potential distribution isformed on the display substrate 121, and the liquid optical material 114is selectively coated by using attraction force and repulsive forcebetween the potential distribution and the positively charged liquidoptical material 114, thereby improving the patterning precision.

Particularly, in this embodiment, since the liquid optical material 114is charged, the effect of improving the patterning precision is furtherincreased by using not only spontaneous polarization but also electriccharge.

Although in this embodiment the invention is applied to an active matrixtype display device, the invention can also be applied to a passivematrix type display device.

This embodiment may further comprise the step of transferring thestructure formed on the peeling substrate 121 through the peeling layer152 onto the display substrate 121.

Also, in this embodiment, the desired potential distribution is formedby successively applying a potential to the scanning lines 131, and atthe same time, applying a potential to the signal lines 132 and thecommon current supply lines 133, and applying a potential to the pixelelectrodes 141 through the switching thin film transistor 142 and thecurrent thin film transistor 143. Since the potential distribution isformed by using the scanning lines 131, the signal lines 132, the commoncurrent supply lines 133 and the pixel electrodes 141, an increase inthe number of the steps can be suppressed. In a passive matrix typedisplay device, the potential distribution may be formed by using thefirst bus lines or the light shielding layer.

Although, in this embodiment, a potential is applied to both the pixelelectrode 141 and the peripheral interlevel insulation film 240, thepresent invention is not limited to this. For example, as shown in FIG.13, a positive potential may be applied only to the interlevelinsulation film 240, with no potential applied to the pixel electrode141, and then the liquid optical material 114 may be coated after beingpositively charged. In this case, since the liquid optical material 114can securely be maintained in a positively charged state after coating,it is possible to securely prevent the liquid optical material 114 fromflowing out to the periphery due to the repulsive force between theoptical material 114 and the peripheral interlevel insulation film 240.

Unlike in each of the above embodiments, for example, the difference inheight 111 may be formed by coating a liquid material or forming amaterial on the peeling substrate through the peeling layer and thentransferring the structure peeled off from the peeling layer on thepeeling substrate onto the display substrate.

Although, in each of the above embodiments, an organic or inorganic ELmaterial is used as the optical material, the optical material is notlimited to these materials, and may be a liquid crystal.

INDUSTRIAL APPLICABILITY

As described above, in the present invention, since a liquid opticalmaterial is coated by using a difference in height, a desireddistribution of liquid repellency and lyophilicity, or a desiredpotential distribution, there is the effect of improving the patterningprecision of the optical material.

1. A method of manufacturing a display device, the method comprising:forming a recess on a peeling layer disposed on a peeling substrate soas to form a difference in height between a predetermined position and aperiphery of the predetermined position, the predetermined positionbeing lower than the periphery of the predetermined position; applyingan optical material or a liquid precursor to a surface at thepredetermined positions; and transferring a layer to be transferred ontoa display substrate.
 2. The method of manufacturing a display deviceaccording to claim 1, wherein applying one of the optical material andthe liquid precursor to the surface at the predetermined positions isperformed by an ink jet method.
 3. A method of manufacturing anelectro-luminescent device, the method comprising: forming a recess on apeeling layer disposed on a peeling substrate so as to form a differencein height between a predetermined position and a periphery of thepredetermined position, the predetermined position being lower than theperiphery of the predetermined position; applying an optical material ora liquid precursor to a surface at the predetermined positions; andtransferring a layer to be transferred onto a display substrate.
 4. Amethod of manufacturing a display device, the method comprising:enhancing a lyophilicity at a predetermined position relative to alyophilicity at a peripheral region around the predetermined position ona peeling layer disposed on a peeling substrate; applying one of anoptical material and a liquid precursor to a surface at thepredetermined positions; and transferring a layer to be transferred ontoa display substrate.
 5. A method of manufacturing an electro-luminescentdevice, the method comprising: enhancing a lyophilicity at apredetermined position relative to a lyophilicity at a peripheral regionaround the predetermined position on a peeling layer disposed on apeeling substrate; applying one of an optical material and a liquidprecursor to a surface at the predetermined positions; and transferringa layer to be transferred onto a display substrate.